Hypodermic syringes are used with hypodermic needles to inject liquid or gases into body tissues or to remove blood or other fluid or fluid-like samples from the body. The barrel of a syringe can be made of plastic or glass and usually has graduated marks indicating the volume of fluid in the syringe. The barrel of a syringe is nearly always transparent. Most modern medical syringes are plastic with a rubber piston because this type of syringe seals much better between the piston and the barrel and because they are cheap enough to dispose of after being used only once. Very serious problems can arise with needle re-use especially in use outside of health care settings and use in third world countries.
At least 3 billion injections occur yearly outside of health care settings. About 2 billion of these injections are administered by people with diabetes and patients receiving home health care. Approximately 1 billion are attributed to injection drug users (IDUs) using illicit drugs like heroin and cocaine. Most of the needles used for these injections end up discarded in household trash and community solid waste, putting workers and the public at risk of needle stick injuries and potentially fatal infections. A surprise encounter with a used syringe or needle in a playground, park, or at work can provoke intense fears of injury and life-threatening infections. If a needle stick injury occurs, the costs of providing post-injury counseling and prevention measures are significant. Problems that can arise from unsafely discarded used syringes and needles include needle stick injuries and potentially fatal blood borne infections, such as human immune deficiency virus (HIV) and hepatitis B and C.
Even in a controlled setting such as a hospital or other healthcare facility, an accidental needle stick injury is a constant occupational hazard for healthcare workers and other employees working in such a setting. Although such facilities generally provide disposal containers (e.g., Covidien™ Sharps Containers), improper disposal of syringes and needles can increase the risk of an accidental needle stick injury. For example, a healthcare worker or employee may not be properly educated in the proper disposal of needles or may inadvertently dispose of a used needle in the regular trash. Also, a healthcare worker may sustain an accidental needle stick when administering medication to a patient. In one scenario, a healthcare worker may sustain an accidental needle stick when administering medication to an epileptic patient.
Consequently, a needleshield assembly is needed for rendering a dispensing device, such as a syringe, non-usable after a single use.